1. Field of the Invention
The present invention relates generally to a printed circuit board having an integral connection structure that is used for electrical connection with another board, and, more particularly, to a printed circuit board having integral connectors that can maintain stable connection with another printed circuit board, for which electrical connection is necessary, without requiring the use of separate connectors, and can also realize a reduction in thickness.
2. Description of the Related Art
Generally, a Printed Circuit Board (PCB) functions to conveniently connect various elements for an electronic product using a predetermined pattern, and is widely used for all electronic products ranging from electronic home appliances, including a digital TeleVision (TV), to high-tech communication devices. Such a PCB is classified as a general-purpose PCB, a PCB for a module and a PCB for a package according to the purpose of use.
That is, a PCB is formed in such a way as to construct necessary circuits by attaching a thin layer, made of copper, to one surface of a phenol-resin insulation board, an epoxy-resin insulation board or the like and performing etching on a wiring pattern for circuits, and bore holes for mounting elements, and is classified as a single-sided PCB, a double-sided PCB, or a multilayer PCB according to the number of wiring circuit surfaces. A PCB having a large number of layers is applied to high-precision products because the ability to mount components is excellent. Recently, with the development of the electronics industry, an ultra-thin PCB having a thickness of 0.04 mm˜0.2 mm has been widely used.
A single-sided PCB is used for relatively simple electronic devices. However, recently, the use of a double-sided PCB, in which circuits are formed on both surfaces thereof and are connected to each other via through-holes, or a multilayer PCB, which is realized by expanding the double-sided PCB to a plurality of layers instead of just two surfaces, has increased.
A method of manufacturing a PCB, which is generally known, is briefly described below. An original clad board, which is formed by applying a copper foil having a thickness on the μm scale on an insulation board, is used. A pre-treatment step, a through-hole processing step, an electroless plating step, a circuit printing step, an etching step, and a post-treatment step are performed on the original clad board.
Here, the pre-treatment step is a step of cutting the clad board and preparing a full-scale PCB manufacturing process. Through-holes are formed in the original clad board, which is cut to an appropriate size at the pre-treatment step, using a drill, and then thin copper foils are formed on the respective surfaces of the through-holes formed at the pre-treatment step using electroless plating. This makes electro copper plating possible later.
Subsequently, at the circuit printing step, a photoresist film is applied on the original clad board, portions of the original clad board other than copper circuit portions and through-hole portions in a previously designed wiring diagram are masked by exposing and developing them, and then a protection layer for protecting the copper foils of the circuit portions is formed by performing solder plating or nickel and gold plating on the resulting structure. Thereafter, at the etching step, the photoresist film mask is removed, and only circuit wiring is allowed to remain by etching copper portions other than the circuit portions. In the case where a solder plating layer is formed, the solder plating layer is removed. Thereafter, at the post-treatment step, the process of manufacturing a PCB board is completed through intermediate inspection, routing, and final inspection.
Meanwhile, with the recent trend toward small-sized and lightweight electronic products, various types of connectors are used to dispose two or more circuit boards at different locations and electrically connect the circuit boards.
As an example, a Rigid Printed Circuit Board (RPCB), on which a main circuit and electronic components are mounted, and a Flexible Printed Circuit Board (FPCB), on which modular electronic components are mounted and which has a desirable bending characteristic, are individually manufactured, and then a connector is used to electrically connect the RPCB and the FPCB to each other.
FIG. 1 is a diagram showing the structure of a prior art connector for electrically connecting an RPCB and an FPCB.
As shown in FIG. 1, the connector 200 for electrically connecting circuit boards, for which electrical connection is necessary, is illustrated. The connector 200 is disposed between a main circuit board 100, which is used to mount a main circuit and principal components thereon and is provided as a typical RPCB, and the rigid part 155 of an auxiliary circuit board 150, which is used to mount auxiliary circuits and modular electronic components thereon and is provided as an FPCB, and is configured to connect the main circuit board 100 and the rigid part 155 to each other.
The connector 200 includes a housing 210, which is made of synthetic resin, such as plastic, and is formed using injection molding, and is configured such that a predetermined space is formed in the housing 210, and elastic workpieces 230 are accommodated in the housing 210 so that both ends of the workpieces 230 protrude elastically in the both direction of both side the housing 210.
That is, the connector 200 electrically connects the main circuit board 100 and the auxiliary circuit board 150 in such a way that one end of each elastic workpiece 230 is jointed to the pad part 110 of the main circuit board 100 using solder, and the other end of each elastic workpiece 230 comes into elastic contact with the rigid part 155 of the auxiliary circuit board 150.
Meanwhile, the main circuit board 100 and the sub circuit board 150 are mechanically coupled to each other using a screw fastening structure in the state in which the connector 200 is disposed therebetween.
However, the prior art connector 200, described above, is provided with the plurality of elastic workpieces 230 in the housing 210, and thus the structure thereof is complicated. Furthermore, one end of each elastic workpiece 230 must be fastened to the main circuit board 100 using soldering, and thus the operation efficiency is low. As a result, there are disadvantages in that an electrical signal transmission characteristic is degraded and a high manufacturing cost is required.
In particular, the connector basically makes a structure thick. As a result, there are limitations to the reduction of the size of electronic products that employ the connector.